T3 kinetics in euthyroid Graves' disease patients who exhibit hyper-responsiveness to TRH after radioiodine treatment.
A major reduction in T3 turnover has been demonstrated previously in clinically hypothyroid patients. We have used non-compartmental (NC) and monocompartmental (MC) analysis to study ten patients with Graves' disease who, following treatment with radioactive iodine (RAI), are now clinically euthyroid but who showed hyper-responsiveness to TRH although serum T3 and T4 concentrations are within the normal range. T3 production rate (PR), metabolic clearance rate (MRC) and fractional-turnover (K) were all significantly reduced in patients compared with seven controls (P less than 0.01). T3, MCR and PR were consistently higher, and T3 K lower, when calculated by MC, than values calculated by NC analysis. The difference in T3 production rates between patients (mean 16.6 nmol/day) and controls (mean 38.9 nmol/day) raises the question of replacement therapy in patients who are apparently euthyroid but TRH hyper-responsive.
D000328:Adult; D000368:Aged; D005260:Female; D006111:Graves Disease / Q000378:metabolism* / Q000532:radiotherapy; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D007700:Kinetics; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D013972:Thyrotropin / Q000097:blood; D013973:Thyrotropin-Releasing Hormone; D014284:Triiodothyronine / Q000378:metabolism*
D007457:Iodine Radioisotopes; D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin